It gets better, even if you change the MX entries, there is no guarantee that GMail will deliver mail to those new servers because the domain may still exist in their system. So you may remian cut off from a significant number of people.
No, spindritf has a point. If a MTA is configured to consider a domain as "local" it will route emails internally instead of doing MX lookups. It's likely more complex in this case, but essentially it can mean that any emails routed through Google's systems (Gmail and Google Apps for Domains) will keep bouncing as long as the domain is configured, even if you've changed MX records to a different MTA.
Based on the quality of other Google products, I think it's safer to assume the inverse: Google's mail servers likely know about a domain's MX records and adjust accordingly without account configuration or external intervention.
Maintaining a system as large as the one they do without this feature would seriously suck for the mail admin - it really has nothing to do with the customer at that point. I wouldn't want to work that job if it did because of a) all the angry people it affected and b) the overhead in my job introduced by a bad programmer.
This is a fact seen in practice. You can check it if you want. Just create Google Apps account and configure mail without setting any MX records in your DNS. You will be able to send and receive emails to and from that account and regular Gmail account.
Not a complete counter example, but on a domain I run with external mail, gmail enabled but MX never setup, sending a email with google apps gmail, from me@mydomain to you@mydomain sends the email to the external provider
I believe spindritf is indicating that google doesn't use the "open internet" for gmail <-> gapps, it's all routed internally. If they find your domain registered within their system they skip the lookup.
> Is that speculation or do you know it will happen?
I had troubles a few years back with e-mail routing from GMail to mail servers for a domain that had previously Google Apps set up for it but was subsequently moved to another provider. They disappeared after deleting Google Apps.
Maybe it's not an issue any more, maybe it was just some weird caching problem, maybe disabled domains are handled differently but it wouldn't also surprise me if they had some system for handling what is essentially mail internal to GMail.
Exchange will ignore MX records and deliver directly to accounts that exist in AD. This is true for some other email systems as well like Mirapoint. I'm not sure about Gmail.
When I set set up my email account at google apps few years ago my MX records were messed up, so no mail could be delievered to my new google app address from outside gmail. However, my regular test gmail account was happily sending emails that were received on my apps account although MX records were messed.
Thinks might have changed in the meantime, but my guess is that Google still sends emails directly for accounts that it "knows" are hosted on gmail and apps and happily ignore MX records.
You just made this FUD up. Google uses MX records to send to Apps customers, because some of them run their mail through third-party services and proxies.
Imagine an events services company (like the one I am working for) which is 100% dependent in business operations from email and website availability during the event or marketing phase. It would be an assassination for us, and I thank the author for the warning. We shall not use Google Apps as a company for this reason.
To be fair to Google, this was hardly an assassination...